1. Field of the Invention
This invention relates generally to impact detection upon a toy or game playing surface and more specifically to the electronic detection of impacts, upon a playing surface of a toy or game using piezo electric sensor elements.
2. Background-Description of Prior Art
For sometime manufactures of toys and games, have had a need for a method to detect impacts of projectile game elements such as balls, darts, etc., upon a target or game surface. Such a method should be inexpensive, of reliable function, with ease of manufacture and assembly. It is further desireable for the method to use a minimum of electronic support parts, used in accompanying electronic detection circuitry. As well it should be relatively free from false detection due to extraneous causes such as shock Many attempts of solving this need have used piezo electric sensor elements in a detection role. However the manner in which they are used does little to satisfy the needs set forth. Some examples of prior art methods using piezo electric sensor elements are set forth in the patents briefly described below.
The Landsman U.S. Pat. No. 4,822,042 and the Scharer U.S. Pat. No. 4,361,330 shows the use of piezo electric sensor elements to detect impacts upon a game surface or target. These are used as shockwave detectors, with support electronic circuitry to determine its approximate impact upon a target or game surface location Basic X-Y vector components are provided by the difference in time that it takes the shock wave or sonic wave to travel to each of the few sensors. This method usually requires sensor amplification to attain usable signal levels. This method becomes very suceptable to false triggerings, due to extraneous vibrations from handling or impacts themselves.
The Conrey U.S. Pat. No. 4,101,132 and the Bon U.S. Pat. No. 4,029,315 both show the use of piezo electric sensors utilized to measure the change in tension in a cable member, connected to the target. Which in conjunction changes in response to a projectile stiking the target or game area. Again the difference in time required to trigger the sensors upon the cable elements, is used to determine an approximate X-Y coordinate upon the target or game surface. These systems also usually require sensor amplification to get the sensor signals to levels useable by a detection circuit. These systems would most likely be susceptible to cable element load variances and binding, as well as cable element elasticity, both of which can cause detection errors. These systems should also be susceptible to false triggerings, by sonic vibrations and handling.
In the afore mentioned Patents the methods of detecting impacts specifies that it uses the onset of the shock or sonic waves through the material to the closest sensor element. From there further sensor elements detect the shock or sonic wave, as it moves away from the impact thus determining the distance from each sensor, thereby being able to determine the approximate location of the impact. My method uses the uniform inward compression of a region and thereby the uniform inward compression of an attached piezo electric sensor element. This signal is considerably stronger and thereby more uniform and reliable. An intuitive understanding of the two different components is; if you take a piece of paper and bend it, you can simultaneously instigate a shock or sonic wave through it while not affecting the bending of the paper. While the above Patents utilize the measurement of the shock or sonic waves, my method utilizes the uniform bending of the piezo electric sensor elements. A piezo electric sensor element produces electrical energy by a simple bending of its structure, the greater and more uniformly you can bend it, the larger the electrical signal it will produce. A shock wave produces a sinusoidal motion through a surface. This causes some of the piezo electric sensor element to be bending in the opposite direction shortly after the shockwave begins to effect the piezo electric sensor element. Thereby producing a signal that is relatively small, because negative and positive signals present in the sensor are summed up. This produces only a signal that is as large as the amount of the summed signal components, taking place in the sensor element, as the shock wave strikes the piezo electric sensor element and moves through it. My method is superior since it uses an entire compression of the piezo electric sensor in one direction, this causes a much larger signal. Which is more reliable for detection, while being relatively immune to false triggerings from shock waves. This is further enhanced, because as an impact takes place upon my design, the panels which are not struck bend outwardly as a reaction to the impact. This produces a signal that is of opposite polarity to that of the impacted sensors signal. These panels then vibrate back and forth from being impacted producing a mechanical oscillation that diminishes rapidly, with resultant signals coming from each panel. Using my method, the impact generated shock waves have little effect upon the detection method, as the signals produced by such shock waves are not of sufficient levels to trigger the electronics typically used in my method.
The French U.S. Patent Nos. 4,761,005 and 4,824,107 show the use of piezo electric film used as sensors, in foam garments to detect impacts generally upon various parts of the body. The sensor utilizes a compressive or bending motion in this embodiment, in which to produce an electric signal from the piezo electric film. However it uses a good deal of distance in which to separate the strike areas from other strike areas or nondetection areas. Without the benefit of a flex barrier as my method incorporates, the foam garments they utilized when impacted in a target or non target area and the bodies reaction to the impact, will cause considerable bending and creasing of the garment in the target areas. This will cause the piezo film to also bend and crease and will result in false triggerings from the piezo electric film sensors.